Piston pumps, in particular for the injection of fuel into internal combustion engines



March 5, 1963 J. P. RAIBAUD PISTON PUMPS, IN PARTICULAR FOR. THE INJECTION 0F FUEL INTO INTERNAL COMBUSTION ENGINES Filed Nov. 7, 195a /I\/VE N TOR JEAN PIERRE RAIBAUD GYM? v ATTORNEY United States Patent 3,979,362 PISTON PUMPS, IN PARTICULAR FGR THE INJEC- TEON 9F FUEL IN'H) ETERNAL COMBUSTEGN ENGINES Jean Pierre Raihaud, Le Kremlin-Bicetre, France, assignor to Society Precision Mecanique Lahinal, Saint-Galen, France, a society of France Filed Nov. 7, 1958, Ser. No. 772,469 4 (Iiaims. (Cl. 103-41) The present invention relates to piston pumps, more especially for the injection of fuel into internal combustion engines, of the kind in which the conditions of delivery to the utilisation devices or apparatus (injectors or the like) are adapted to be modified by the action of at least one auxiliary piston acting as a slide valve cooperating with intake and/ or discharge ports, said auxiliary piston being actuated in suitable manner in accordance with the displacements of the main piston.

The object of the present invention is to provide a pump of this kind in which the beginning of fuel injection is advanced with respect to the cycle of operation of the pump in response to an increase of the speed of operation of the pump.

For this purpose, according to the present invention, the auxiliary piston is movable in a corresponding auxiliary cylinder in response to the delivery strokes of the main piston of the pump in its cylinder, the return strokes of said auxiliary piston being produced by resilient means and the liquid discharged from said auxiliary cylinder during the return strokes of the auxiliary piston being made to flow through a throttled passage so that for speeds of operation of the pump above a given value a portion of this liquid no longer has time to flow out from said auxiliary cylinder through said throttled passage during the return strokes of the auxiliary piston, which are thus shortened so as to advance the beginning of fuel injection.

A preferred embodiment of the present invention will be hereinafter described with reference to the accom panying drawing, given merely by way of example and in which:

The only FIGURE shows, in diagrammatic axial section, a pump made according to the present invention for use as a fuel feed pump for an internal combustion engine.

The pump illustrated by the drawing includes at least one main piston 1 fitting slidably in a main cylinder 31 so as to form therewith a variable volume chamber 32, this piston 1 being capable of feeding fuel successively to several delivery conduits such as conduit 2 leading to injector 3, said piston having, for this purpose, in addition to its reciprocating movement, a movement of continuous rotation (see arrow F) to ensure distribution to said conduits through a lateral groove such as 4.

There is further provided at least one auxiliary piston 5 acting as a regulating slide valve capable, by cooperation with suitable orifices or ports, of modifying the conditions of delivery. This auxiliary piston 5 fits slidably in an auxiliary cylinder 33 formed in the same body as the main cylinder 31.

Auxiliary piston 5 (the angular position of which is adjustable) includes distributing edges 24, 25, capable of cooperating with two ports 6 7 port 6 being a fuel feed port in communication with a fuel tank and port 7 a liquid discharge port. In the lower position of auxiliary piston 5 as shown by the drawing, admission (A) takes place through port 6 opening opposite an annular groove 26 of the slide valve, said groove being itself connected to the variable volume chamber 32 of the pump through conduit which opens into auxiliary cylinder 33 through an inlet opening 34. The beginning of injection takes place when the edge 24 of piston 5 comes to shut off intake port 6 The liquid is placed under pressure and driven by piston 1 through the distributing groove 4. The end of injection is produced by discharge (R) when the edge 25 of piston 5 comes to uncover port 7 and places it in communication with groove 26 and conduit 15. Auxiliary piston 5 is reciprocable in an auxiliary cylinder formed in the pump body and ending in a space 27.

The displacement of piston 5 is obtained by hydrodynamic effect under the action of a piston 16 rigid with piston 1 and cooperating with a feed cylinder formed in the main pump body, the variable volume chamber limited by piston 16 in its cylinder being connected through a conduit 17 with space 27.

In this conduit 17, there is provided a check valve 28. A discharge or return circuit 2?, 3% is provided between space 27 and the cylinder of piston 16, this circuit including a throttled passage x which is advantageously controlled by a pilot valve 22 or any other means.

It will be seen that, at low speeds, the throttled sec tion x has practically no effect. When piston 16 is driven into its cylinder, piston 5 is lifted upwardly to perform its distributing action. During the return movement of piston 16, valve 23 closes so that the liquid, under the effect of the downward movement of piston 5 produced by its spring 12, is compelled to escape from chamber 27 through the return circuit 29, 30 (discharge r). The throttled passage x exerts practically no effect so that the slide valve can return to its lowest position.

On the contrary, when the speed increases, the relative eifect of the throttled passage as becomes more and more important so that the auxiliary piston is braked during its downward movement and can no longer return to its lowest position. This produces an automatic advance of the beginning of injection in response to an increase of the speed.

If necessary, the throttied section at may itself be adjusted as a function of the speed or of another parameter. On the drawing, valve 22 has been shown as being controlled by a centrifugal governor 23.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and eflicient embodiment of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What I claim is:

1. A reciprocating piston liquid pump which comprises, in combination, a main cylinder and a reciprocating main piston fitting slidably in said cylinder so as to form therewith a variable volume chamber, the displacements of said piston with respect to said cylinder which reduce the volume of said chamber being called the delivery strokes of said piston, a delivery conduit in communication with said chamber, an auxiliary cylinder faxed with respect to said main cylinder, an auxiliary piston fitting slidably in said auxiliary cylinder, hydraulic means operatively connected to said main piston and arranged to act on said auxiliary piston so that every delivery stroke of said main piston causes a displacement of said auxiliary piston in one direction, resilient means connected with said auxiliary piston for urging it in the direction opposed to said first mentioned direction, said auxiliary cylinder and piston being arranged to form between them a variable volume space which increases during the displacements of said auxiliary pistwin said first mentioned direction and decreases during the displacements of said auxiliary piston in said second mentioned direction, said last mentioned displacements of said auxiliary piston being called return strokes thereof, a liquid feed .port opening into said. auxiliary .cylinde'r near one end thereof, a liquid discharge port in said auxiliary cylinder near the other end thereof, said auxiliary cylinder being provided with an inlet opening located'at a point thereof intermediate between said ports, conduit means leading from said variable volume chamber of said main cylinder to said auxiliary cylinder inlet opening, said auxiliary piston being in the form of a slide valve provided with a passage arranged to connect said inlet opening with said feed port at the beginning of .every movement of said auxiliary piston in said first mentioned direction, then to cut oil? said inlet opening from both of said ports for a portion of said last mentioned movement and finally to connect said inlet opening with said discharge port at the end of said last mentioned movement, and liquid discharge means in ,communication,.during the return strokes of said auxiliary piston, with the portion of said auxiliary -cylinder limiting said variable volume space, said liquid discharge means forming the only way for the outflow of liquid from said space during said return strokes of said auxiliary piston and said liquid discharge means including a throttled passage for braking the outflow therethrough of liquid from vsaid space, whereby, for speeds of reciprocation of said main piston above a given value, "said throttled passage in said liquid discharge means permits only a portion of the liquid present in said variable volume space to be discharged therefrom during every return stroke of said auxiliary piston and thus limits said return stroke so that on the next delivery-stroke of said main piston said conduit means opening is cut oif'from said liquid intake port at an earlier time during every cycle of operation of'the pump.

'2. A pump according to claim 1 in which said means for hydraulically connecting said auxiliary piston with said main piston include a feed cylinder rigid with said main cylinder, a feed piston rigid with said main piston and fitting slidably in said feed cylinder so as to form therewith a variable volume feed chamber, a liquid 'feed conduit opening into the pprtion of said feed cylinder limiting said feed chamber, a conduit leading from said portion of said feed cylinder to the portion of said auxiliary cylinder limitingsaid variable volume space and a check valve in said last mentioned conduit arranged to permit flow of liquid only from said feed chamber toward said variable volume space.

3. A pump according to claim 1 in which said means for hydraulically connecting said auxiliary piston with said main piston include a feed cylinder rigid with said main cylinder, a feed piston rigid with said 'main piston and fitting slidably in :said feed cylinder so as to form therewith a variable volume feed chamber, a liquid'feed conduit opening into the portion of said feed cylinder limiting said feed chamber, a conduit leading from said portion of said feed cylinder to the portion of said auxiliary cylinder'limiting said variable volume space and a check valve in saidlast mentioned conduit arranged 'to'permit flow of liquid only "from said feed chamber toward said variable volume space, said liquid discharge means leading from the portion of said auxiliary cylinder limiting said variable volume space to the portion of said feed cylinder forming vsaid feed chamber. 4. A pump according to claim 1 further comprising adjusting means for varying the cross-section area of said throttled passage and governor means responsive to variations of the speed of reciprocation of said main piston for controlling said adjusting means in accordance with said speed variations.

Outin Apr. "28, 1942 Bessiere June '14, 1960 

1. A RECIPROCATING PISTON LIQUID PUMP WHICH COMPRISES, IN COMBINATION, A MAIN CYLINDER AND A RECIPROCATING MAIN PISTON FITTING SLIDABLY IN SAID CYLINDER SO AS TO FORM THEREWITH A VARIABLE VOLUME CHAMBER, THE DISPLACEMENTS OF SAID PISTON WITH RESPECT TO SAID CYLINDER WHICH REDUCE THE VOLUME OF SAID CHAMBER BEING CALLED THE DELIVERY STROKES OF SAID PISTON, A DELIVERY CONDUIT IN COMMUNICATION WITH SAID CHAMBER, AN AUXILIARY CYLINDER FIXED WITH RESPECT TO SAID MAIN CYLINDER, AN AUXILIARY PISTON FITTING SLIDABLY IN SAID AUXILIARY CYLINDER, HYDRAULIC MEANS OPERATIVELY CONNECTED TO SAID MAIN PISTON AND ARRANGED TO ACT ON SAID AUXILIARY PISTON SO THAT EVERY DELIVERY STROKE OF SAID MAIN PISTON CAUSES A DISPLACEMENT OF SAID AUXILIARY PISTON IN ONE DIRECTION, RESILIENT MEANS CONNECTED WITH SAID AUXILIARY PISTON FOR URGING IT IN THE DIRECTION OPPOSED TO SAID FIRST MENTIONED DIRECTION, SAID AUXILIARY CYLINDER AND PISTON BEING ARRANGED TO FORM BETWEEN THEM A VARIABLE VOLUME SPACE WHICH INCREASES DURING THE DISPLACEMENTS OF SAID AUXILIARY PISTON IN SAID FIRST MENTIONED DIRECTION AND DECREASES DURING THE DISPLACEMENTS OF SAID AUXILIARY PISTON IN SAID SECOND MENTIONED DIRECTION, SAID LAST MENTIONED DISPLACEMENTS OF SAID AUXILIARY PISTON BEING CALLED RETURN STROKES THEREOF, A LIQUID FEED PORT OPENING INTO SAID AUXILIARY CYLINDER NEAR ONE END THEREOF, A LIQUID DISCHARGE PORT IN SAID AUXILIARY CYLINDER NEAR THE OTHER END THEREOF, SAID AUXILIARY CYLINDER BEING PROVIDED WITH AN INLET OPENING LOCATED AT A POINT THEREOF INTERMEDIATE BETWEEN SAID PORTS, CONDUIT MEANS LEADING FROM SAID VARIABLE VOLUME CHAMBER OF SAID MAIN CYLINDER TO SAID AUXILIARY CYLINDER INLET OPENING, SAID AUXILIARY PISTON BEING IN THE FORM OF A SLIDE VALVE PROVIDED WITH A PASSAGE ARRANGED TO CONNECT SAID INLET OPENING WITH SAID FEED PORT AT THE BEGINNING OF EVERY MOVEMENT OF SAID AUXILIARY PISTON IN SAID FIRST MENTIONED DIRECTION, THEN TO CUT OFF SAID INLET OPENING FROM BOTH OF SAID PORTS FOR A PORTION OF SAID LAST MENTIONED MOVEMENT AND FINALLY TO CONNECT SAID INLET OPENING WITH SAID DISCHARGE PORT AT THE END OF SAID LAST MENTIONED MOVEMENT, AND LIQUID DISCHARGE MEANS IN COMMUNICATION, DURING THE RETURN STROKES OF SAID AUXILIARY PISTON, WITH THE PORTION OF SAID AUXILIARY CYLINDER LIMITING SAID VARIABLE VOLUME SPACE, SAID LIQUID DISCHARGE MEANS FORMING THE ONLY WAY FOR THE OUTFLOW OF LIQUID FROM SAID SPACE DURING SAID RETURN STROKES OF SAID AUXILIARY PISTON AND SAID LIQUID DISCHARGE MEANS INCLUDING A THROTTLED PASSAGE FOR BRAKING THE OUTFLOW THERETHROUGH OF LIQUID FROM SAID SPACE, WHEREBY, FOR SPEEDS OF RECIPROCATION OF SAID MAIN PISTON ABOVE A GIVEN VALUE, SAID THROTTLED PASSAGE IN SAID LIQUID DISCHARGE MEANS PERMITS ONLY A PORTION OF THE LIQUID PRESENT IN SAID VARIABLE VOLUME SPACE TO BE DISCHARGED THEREFROM DURING EVERY RETURN STROKE OF SAID AUXILIARY PISTON AND THUS LIMITS SAID RETURN STROKE SO THAT ON THE NEXT DELIVERY STROKE OF SAID MAIN PISTON SAID CONDUIT MEANS OPENING IS CUT OFF FROM SAID LIQUID INTAKE PORT AT AN EARLIER TIME DURING EVERY CYCLE OF OPERATION OF THE PUMP. 